A method of cooking food, in particular a grain such as rice, is generally known, and may be carried out by a device which is adapted to be filled with quantities of food and water. For the purpose of cooking rice, many types of rice cookers are available, including electrical rice cookers which comprise electrical heating elements for providing the heat that is necessary in a cooking process, and means for controlling the cooking process. In the case of a conventional electrical rice cooker, when a user wants to cook a quantity of rice, the user fills a space of the rice cooker with the quantity of rice and an appropriate quantity of water, and subsequently activates the rice cooker to heat the mixture of rice and water during a period of time. During operation of the rice cooker, the mixture of rice and water is heated to such an extent that the water starts to boil, so that the rice is continuously heated at the boiling temperature of the water.
According to a known method of decreasing the period of time during which the rice is cooked, a rice cooking process is performed at a higher temperature. In normal circumstances, the boiling temperature of water is 100° C., but, according to thermodynamic laws, the boiling temperature is increased when ambient pressure is increased. In view of this, rice cookers which are adapted to be used as a pressurized cooking pan have been developed. Usually, a pressurized rice cooker comprises a mechanism for firmly pressing a lid of the pan in a position for closing the pan. Pressure is built up during a cooking process on the basis of the formation of steam which takes place during a boiling process of the water, as this steam is not allowed to escape from the pan. In this way, the boiling point of the water may be increased to 110-120° C., namely when a pressure up to about 2 bar is realized.
In a conventional rice cooker, heating up the mixture of rice and water takes approximately 10 minutes, and an actual rice cooking process takes approximately 20 minutes. In a pressurized rice cooker, when the water is boiled to a temperature of 100-120° C., the actual rice cooking process only takes approximately 10 minutes. This means that the total time that is needed for cooking rice is considerably reduced. However, the heating up of the mixture of rice and water for the purpose of initiating an actual cooking process still takes approximately 10 minutes. Hence, in a pressurized rice cooker, the time needed for initiating a cooking process is in the same order as the time needed for performing the actual cooking process.